The Slavs, like all the other Indo-European-speaking peoples whom we have been able to trace, were originally Nordic, and there is no suggestion in their early remains, in the regions studied, of the numerically predominant brachycephalic racial increments which today are considered typically Slavic. Most of the Slavs retained their original dolichocephalic cranial form until at the earliest the thirteenth, and the latest the fifteenth, century. At that time, those who inhabited Russia and central Europe grew progressively brachycephalic, at a rapid but consistent rate. Well-documented series from Bohemia and the Moscow government show how this change progressed from century to century, so that normal means of 73 to 75 rose as high as 83 by the nineteenth. Few Slavs were spared this change, which was parallel to that which affected the southern Germans and other peoples of central and eastern Europe. Although it took place in the full light of late mediaeval and modern history, no one fully satisfactory explanation has yet been offered.

Carleton Coon, The Races of Europe

This makes extremely clear the almost pure Aryan origins of Slavs, something not quite as apparent once someone confronts contemporary evidence alone.

This is yet another argument to the fact Aryans DID exist, they DID impose their race (not only language and culture) upon culturally and demographically inferior groups throughout Europe.